Socket connectors



Oct. 28, 1958 s. G. YOUNG SOCKET CONNECTORS Filed Jan. 19-, 1954 United States Patent I 2,858,521 SOCKET CONNECTORS Sidney Geoffrey Young, London, England Application January 19, 1954, Serial No. 405,014.

14 Claims. (Cl. 339255) This invention relates to improvements in the construction of socket connectors of the type employed to grip a pin connector resiliently, in order to establish an electric circuit; and is more especially applicable to electric plug and socket unions having a plurality of pins, as in the conventional two and three pin electric power plugs.

It is the object of the invention to provide socket connectors which when employed to receive the pins of such multi-pin plugs will provide satisfactory electrical and mechanical performance in spite of the variations which may occur in practice in the distances between the centre-lines of the pins of different plugs. It is necessary in order to accommodate such manufacturing variations in the distances between the pins, and also any slight variations in the diameters of the pins themselves, to provide a socket of very adaptable character, a feature which has never been satisfactorily exhibited by the socket connectors commercially available hitherto, since itis equally essential from a commercial viewpoint that such adaptability be combined with the greatest possible simplicity of manufacture and assembly together with economy of materials.

I have now developed a socket connector in which these objects are achieved to a degree far in excess of any prior proposal, and the preferred construction of this connector is illustrated in the annexed drawing, so that the features thereof may be clearly understood.

In said drawing:

Figure 1 shows a perspective view of said connector with a plug pin withdrawn from engagement therewith.

Figure 2 is the same as Figure 1 after the pin has been inserted in the connector;

Figure 3 is a section taken along the line IIIIII in Figure 1 with the addition of a mounting for the connector;

Figure 4 is a view, showing atypical arrangement of three such connectors for the reception of a standard three pin plug;

Figure 5 is a diagrammatic side view of the arrangement shown in Figure 4 with a plug inserted; Figure 6 is an enlarged plan view of the connector shown in Figure 1 showing more details;

Figure 7 is'a view similar to Figure 6 demonstrating the effect of the insertion of a pin into the connector; and

Figure 8 illustrates a modification.

; Considering the socket connector broadly with reference to Figures 1 to 3, it will be seen to comprise a terminal post 1, e. g. of brass, having a hole 2 extending therethrough either coaxially or parallel to the axis, into which hole a conductor (not shown) may be inserted and secured by means of a binding screw 3. This terminal post 1 is embraced by a spring 4, e. g. of Phosphor bronze, which is so shaped as to provide a space 5 between itself and an inwardly curved surface 6 on the outer surface of the terminal post, into which space 5 a a pin '7 may be inserted as shown in Figure 2. A flange Patented Oct. 28, 1958 8 on the post prevents the spring 4 sliding off the terminal post 1 when the pin 7 is withdrawn, while the spring is made slightly narrower than its seating on the post 1, as demonstrated by the space 9 at the bottom, so as not to clamp the spring and prevent its moving relatively to the post when the connector is mounted on an insulating base 10 which is part of a casing, which base is shown in Figure 3 and which casing is shown in section in Figure 5, such mounting being accomplished by spinning over the end of an extension piece 11 of the post 1, to form a flange 12. The upper edge of the surface 6 may be chamfered, as shown at 18, to facilitate entry of the pin.

As stated above, Figure 4 shows a typical arrangement of three such connectors for receiving a standard three pin plug, one pin of which (the earth pin) is longer and of greater diameter than the other two pins (the line and neutral pins). The connectors which re- .ceive the smaller pins are disposed side by side, so that any variation from the correct distance D apart of the pin centre-lines, that the pins of the plug may have, is absorbed by movement towards or away from each other of the two springs 4, these springs being freely rotatable about the posts 1 within the limits imposed by the screws 3 against which their ends will impinge. In a similar manner, the distance D that the centre-line of the larger pin should be from the line joining the centres of the smaller pins, may also be varied within limits as a result of the freedom that the spring 4 of the larger connector has to rotate about its post 1'.

Figure 5 shows a side view of the arrangement shown in Figure 4 with a plug 13 in position. The shorter pins 14 of this plug abut against the base 10 which forms part of a casing, while the longer pin 15 is accommodated in a hole extending through the base 10 adjacent the hole therein through which the extension piece, having a flange 12, of the larger connector extends. It is of particular importance to note that the overall depth A of the socket assembly is substantially the same as the length of the longer pin 15, so that this depth has thus been reduced to the absolute minimum possible for any given plug. This feature which provides an important saving of materials is the result of the very compact side-by-side arrangement of the springs and terminal posts of the socket connectors employed.

For consideration of the exact shape of the connectors illustrated reference should be made to Figures 6 and 7, the former being a view before the insertion of a pin, and the latter with the pin in place. The terminal post 1 is cylindrical in shape except for the flange 8 and the portion cut away to provide the pin contacting surface 6. To allow for misalignment of the pin centre, as is the chief object of the invention, this surface 6 is not a true cylindrical surface described about the theoretical centre line of the pin. It consists preferably, for ease of manufacture and advantageous performance, of segments of two cylindrical surfaces described about two lines E and F each displaced a little to one side of the theoretical centre C. The distance between these lines is exaggerated somewhat for demonstration in Figure 6 where such lines are represented by points, the portion of the surface 6 on the left of the centre point 16 having the line E as a centre and the portion to the right being described about the line F' It will of course be understood that the distance between E, C and F may be adjusted to suit the tolerance of centre line error and pin diameter acceptable in the plug, and it is important to note that any other arcuate surface whether simple or complex can be used instead of the segments of two cylindrical ones described, provided the essential feature is present that the distance G is greater than the corresponding dimension on the pin to be employed therewith, that is to say a cylindrical pin when touching the point 16 will have some play, i. e. Will not touch both ends of the curved surface 6 simultaneously. For example, such surface may, as an alternative, consist of a single segment of a cylindrical surface described about a line H displaced beyond the line C. Since the socket connectors will normally be designed to receive the pins of a plug the dimensions and tolerances of which are standardised in accordance with regulations from time to time in force, it will be a simple matter to arrange for the necessary amount of play.

The shape of the spring 4 is also carefully chosen to provide an efficient grip on the pin, and for this purpose it is advantageous to make the dimension K either slightly larger than the pin diameter or such as only to grip the pin lightly at the sides and to make the dimension L somewhat smaller than the diameter of-the pin. T he effect of this arrangement will be seen from Figure 7, wherein a pin 14 is shown inserted, its centre line coinciding with the line E. The spring 4 has beenexpanded radially outwardly with respect to the post 1 and its sides have moved in to grip the pin. In other words the dimension L has become greater than .L, whereas :K' has become less than K; K and L' being of .course equal to each other and corresponding to the diameter of the cylindrical pin 14. In this manner a firm grip of the pin is established by the spring 4, while the .pin is urged strongly against the surface 6 or part thereof. The fact that the spring and the terminal post closely surround and contact almost the whole operative surface of the pin has valuable thermal as wellas electrical advantages, since the heat evolved at the interfaces is rapidly conducted away. The movement of the spring on the post 1, as the pin 14 is inserted, will .be afcombination of a bodily rotation anti-clockwise toallow for the misalignment of said pin, together with an outwards movement of both ends of the spring to accommodate the increase from L to L. These movementscan be appreciated from a comparisonof the ends of the .spring 4 as shown in Figures and 7 in broken lines.

An alternative form of connector is shown diagrammatically in Figure 8. In this form the split in the spring is arranged adjacent the pin. Otherwise the same considerations and dimensions apply as above, aslot .or hole being provided in the spring 17 for passage .of the screw 3. Such hole or slot is of sufiicient widthtopermit rotation of the spring around the post 1 within the limits required.

Having now considered the preferred forms of socket connector, it is to be appreciated that numerous variations are possible within the scope of the invention which calls essentially for a connector comprising a substantially cylindrical terminal post having an outer portion cut away to form a seating for a cylindrical pin, .the seating having play as described above, and a spring. embracing said post in close contact therewith and rotatable relatively thereto, said spring being shaped .to contact said pin preferably over a major portionof the peripheral surface thereof and to urge it against the terminal post when the pin is inserted therebetween.

It is not essential, although advantageous for the reasons pointed out above, that the lead-in conductor be brought into a hole alongside the interface between t-the pin and the post. The axes of the hole 2 and the screw 3 could for example be interchanged, or the extension piece 11 could be thickened and lengthened if necessary to accommodate a fixing screw, or could itself be provided with a screw-thread to cooperate with a corresponding thread of a further conductor.

In addition to its extreme simplicity of design ..with consequent economy of space and materials, the present invention enables a low rate spring (i. e. one in which a comparatively large deflection can be obtained by a comparatively small force) to be used in a small space, thus resulting in low mechanical stresses in conjunction with maximum contact pressure and surface area. Assembly is extremely simple as the spring may be lightly sprung on to the post from the end thereof not provided with a flange, so that no likelihood of stressing the spring beyond its yield point will arise in manufacture.

A further advantage that the present construction exhibits, lies in the fact that the pin on leaving the socket will break contact with the spring before breaking contact with the terminal post, so that any arcing that may take place will occur between the pin and the post and will not affect the spring.

I claim:

1. An electric socket connector comprising a substantially cylindrical terminal post having on an outer portion thereof a depression forming an arcuate non-cylindrical seating for a cylindrical pin, the seating allowing play to such pin, and a spring embracing said post in close contact therewith while being rotatable aroundthe post, the spring being shaped to embrace .the pin and urge it against the seating when the pin is inserted therebetween.

2. An electric socket connector as claimed in claim 1, wherein the spring is in the form of a strap extending from the rear of the terminal post, around one curved side surface thereof to an outwardly bulging portion aligned with the seating, and finally around the other curved side surface to the rear of the terminal post.

3. An electric socket connector as claimed in claim 2, wherein the outwardly bulging portion of the spring is of such dimensions that on insertion of the pin into the space between the seating and such spring, the two ends of the spring are drawn slightly towards the pin and the latter is firmly gripped.

4. An electric socket connector as claimed in claim 1, wherein the spring is in the form of a strap andextends uninterruptedly .across .the rear of the terminal post, the-two ends of the spring being closely adjacent each other in the vicinity of a bulging portionof .the spring aligned with said seating.

5. An electric socket connector as claimed inclaim 1, wherein the spring is arranged closely to embrace the pin over a major portion of the peripheral surface thereof.

6. An electric socket connector assembly comprising a plurality of connectors as claimed in claim 1 adapted and disposed to receive the pins of a standard multipin plug.

7. An electric socket connector assembly as claimed in claim 6, wherein the seatings are in the form of segments of two cylindrical surfaces described about parallel lines spaced on opposite sides of the line along which the centre-line of the respective plug pin is theoretically adapted to pass.

8. The combination with an electric multi-pin vplugof a socket assembly comprising a plurality of socket connectors each comprising a substantially cylindrical terminal post having an outer portion cut away to form an arcuate non-cylindrical seating for a cylindrical .pin of the plug, the seatings being such as to allow-the pins to take up any one of a number of positions between limits defined by the allowable tolerance of the distance between the centre lines of the pins, and each connector having a spring embracing the post in close contact therewith while being rotatable around the post, such springs being. shaped tov embrace the respective pins closely and urge them against the seatings when the plug is in position engaging the socket assembly.

9. An electric socket connector comprising a terminal .post having on its outer periphery a part-cylindrical depression serving as a seating for a cylindrical plug pin, and a spring clip embracing said post, said clip having an expandable bulged portion adapted to embrace both circumferentially and longitudinally an inserted cylindrical pin and to urge the latter against the seating.

10. An electric socket connector as defined in claim 9, wherein the surface of the seating is described about a line extending parallel to and spaced on the side remote from the seating from the line along which the centerline of the plug pin is theoretically adapted to pass.

11. An electric socket connector according to claim 9, wherein the bulged portion of the clip and the seating on the post define a generally cylindrical socket the major portion of whose inner peripheral surface is provided by the bulged portion of said clip.

12. An electric socket connector comprising a terminal post having on its outer periphery an arcuate-shaped, rectilinearly-extendingdepression serving as a seating for a cylindrical pin, and a spring clip embracing said post While being capable of rotary movement about said post, said spring having an expandable bulged portion adapted to define with said seating a socket space departing from the true-cylindrical for receiving and partially circumferentially embracing the pin.

13. An electric socket connector as claimed in claim 12, wherein said bulged portion constitutes a major References Cited in the file of this patent UNITED STATES PATENTS 2,174,682 Beggs Oct. 3, 1939 2,221,651 Pelz Nov. 12, 1940 2,424,966 Buchanan et a1 Aug. 4, 1947 2,762,955 Herzog et a1 Sept. 11, 1956 FOREIGN PATENTS 501,985 France Feb. 9, 1920 

